Multi-component deposits

ABSTRACT

The disclosure describes an example technique that includes cold spraying first particles and second particles of a metal alloy on at least a portion of a surface of a substrate to form a deposit on the surface of the substrate. The first and second particles have been subjected to different heat treatments prior to cold spraying. Cold spraying involves accelerating the first particles and the second particles toward the surface of the substrate without melting or creating other thermally induced changes to a microstructure of the first and second particles. As a result, the first particles form a first, heat-treated component and the second particles form a second non-heat-treated or differently-heat-treated component, and the particles and substrate are not subject to a heat treatment during the cold spray process that may further modify their thermomechanical properties.

TECHNICAL FIELD

The disclosure relates to multi-component deposits and techniques forforming multi-component deposits.

BACKGROUND

Heat treatment processes may be used to alter the physical properties ofa component, such as a mechanical part, after the component has beenformed. In a typical heat treatment process, a fabricated component maybe heated to a predefined bulk temperature, such as a transformationtemperature of the constituent material of the component, held at thetemperature for a period of time to achieve a relatively uniformtemperature throughout the component, and cooled at a predefined coolingrate to achieve a particular transformation of the constituent materialof the component. As a result, the component may include a relativelyuniform set of physical properties different from the initial set ofphysical properties of the component prior to heat treatment.

SUMMARY

The disclosure describes example articles, and techniques and systemsfor forming the example articles, that include a deposit having aheat-treated component and either a non-heat-treated or adifferently-heat-treated component.

In some examples, the disclosure describes an example technique thatincludes cold spraying first particles and second particles of a metalalloy on at least a portion of a surface of a substrate to form adeposit on the surface of the substrate. The first and second particleshave been subjected to different heat treatments prior to cold spraying.For example, the first particles may include particles that haveundergone a heat treatment, while the second particles may includeparticles that have either undergone no heat treatment or undergone adifferent heat treatment than the first particles. Cold sprayinginvolves accelerating the first particles and the second particlestoward the surface of the substrate without melting or creating otherthermally induced changes to a microstructure of the first and secondparticles. As a result, the first particles form a first, heat-treatedcomponent and the second particles form a second non-heat-treated ordifferently-heat-treated component, and the particles and substrate arenot subject to a heat treatment during the cold spray process that mayfurther modify their thermomechanical properties.

In some examples, the disclosure describes an example article thatincludes a substrate defining a surface and a deposit on the surface ofthe substrate in which the deposit was formed using cold spraying. Thedeposit includes a first component and a second component. Cold sprayinginvolves accelerating first particles and second particles of a metalalloy toward the surface of the substrate without creating thermallyinduced changes to a microstructure of the respective first and secondparticles. The first and second particles have been subjected todifferent heat treatments prior to cold spraying.

The details of one or more examples are set forth in the accompanyingdrawings and the description below. Other features, objects, andadvantages will be apparent from the description and drawings, and fromthe claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A is a conceptual cross-sectional view of an example articleincluding a deposit that includes a first component and a secondcomponent.

FIG. 1B is a conceptual cross-sectional view of an example articleincluding a deposit that includes a first component and a secondcomponent.

FIG. 2 is a conceptual and schematic block diagram of an example systemfor forming a deposit on a surface of a substrate by cold spraying firstparticles and second particles of a metal alloy on the surface of thesubstrate.

FIG. 3 is a flow diagram illustrating an example technique for forming adeposit on a surface of a substrate by cold spraying first particles andsecond particles of a metal alloy on the surface of the substrate.

DETAILED DESCRIPTION

The disclosure generally describes example systems and techniques fordepositing heat treated metal alloys and, optionally, non-heat-treatedmetal alloys onto a substrate without exposing the substrate to hightemperatures. The example techniques involve cold spraying metal alloyparticles onto a substrate to form a deposit. These cold sprayed metalalloy particles include a mix of particles having a metal alloy that hasbeen heat treated (“heat-treated particles”) and particles having thesame metal alloy that either has not been heat treated(“non-heat-treated particles”) or has been heat treated with a differentheat-treatment (“differently-heat-treated particles”). Heat-treatedparticles may have properties, such as tensile strength and elongation,that are improved compared to non-heat-treated particles of the samecomposition. In cold spraying, the heat-treated particles,non-heat-treated particles, and/or differently-heat-treated particlesare directed toward and impact the substrate while having temperaturesthat remain below a temperature at which the particles experiencethermally induced property changes. The cold sprayed particles bond withpreviously deposited particles to form a two-component deposit thatincludes a heat-treated component and either a non-heat-treatedcomponent or a differently-heat-treated component.

In some examples, the techniques discussed herein incorporateheat-treated materials into an article without exposing an underlyingsubstrate of the article or materials in the deposit to temperatureconditions experienced during heat treatment processes. For example,deposition of a heat-treated metal alloy layer may involve firstdepositing the metal alloy layer and subsequently exposing both themetal alloy layer and the substrate to heat treatment conditions,including high temperature conditions for extended periods of timeand/or fast cooling conditions. These high temperature and/or fastcooling conditions may damage the substrate and/or produce undesiredchanges in properties of the substrate. Cold spray deposition ofheat-treated particles may occur below the melting point or othertransition temperature of the metal alloy and without bulk heating ofthe underlying substrate or deposited material, such that the underlyingsubstrate or deposited material is exposed to lower temperatures thantechniques that incorporate heat-treated materials onto a substratewithout cold spraying. As such, properties of the heat-treatedparticles, non-heat-treated particles, and/or differently-heat-treatedparticles may be substantially unchanged after cold spraying.

In some examples, the techniques discussed herein incorporate a blend ofvarious heat-treated materials and non-heat-treated materials into anarticle. For example, heat treatment of a metal alloy layer may involvebulk heating the metal alloy layer to a substantially uniformtemperature to produce a metal alloy layer with substantiallyhomogeneous properties. Cold spray deposition of the heat-treatedparticles and differently-heat-treated or non-heat-treated particles mayproduce a deposit that includes properties, such as tensile strength andelongation, derived from the heat-treated material, and either and thenon-heat-treated material or the differently-heat-treated material, suchthat deposits formed from a mix of heat-treated particles anddifferently-heat-treated or non-heat-treated particles may include agreater variety of properties than deposits formed from heat-treated ornon-heat-treated materials alone.

FIG. 1A is a conceptual cross-sectional view of an example article 10Athat includes a substrate 12 and a deposit 14. In some examples, article10A may be a component of a gas turbine engine. For example, article 10Amay be a component with a barrier coating, a repaired component, amulti-layer component, or the like. Due to high temperatures experiencedin gas turbine engine, components of gas turbine engines may incorporateheat treated materials to relieve residual stresses and increase desiredproperties. In some examples, substrate 12 includes a bulk material,such as a forged metal, a cast metal, or a sheet metal, that may besubstantially homogeneous (e.g., homogeneous or nearly homogeneous tothe extent possible by common metallurgy techniques). Bulk materialsthat may be used for substrate 12 include, but are not limited to,Ni-based alloys, Co-based alloys, Ti-based alloys, or Fe-based alloys.Substrate 12 defines a surface 16. Surface 16 may have a variety ofsurface conditions including, but not limited to, an as-manufacturedsurface, a2. damaged surface, or the like.

Deposit 14 is on at least a portion of surface 16 of substrate 12. Whileshown in FIG. 1A as covering an entirety of surface 16, in someinstances, deposit 14 may only cover a particular area, such as aportion of article 10A that may experience abrasion, high temperatures,or other external phenomena that induce stresses and/or fractures.Deposit 14 may represent a one or more of a variety of functionaldeposits of the metal alloy on substrate 12 including, but not limitedto: a structure functionally differentiated from substrate 12, such as aflange or other structure extending from and/or complementary tosubstrate 12; a repair joint of substrate 12, such as a filler; acoating on substrate 12, such as a barrier coating; a layer on substrate12, such as a layer in a multi-layer part; or the like.

In some examples, deposit 14 may be configured to improve properties ofsubstrate 12. For example, substrate 12 may be a damaged componenthaving cracked surface 16 that includes one or more cracks that extendinto substrate 12. Rather than replace substrate 12 with a new part orrepair substrate 12 using high temperature techniques, such as weldingor post-deposition heat treatment, deposit 14 may be formed within theone or more cracks to fill the cracks. As a result, substrate 12 mayhave improved properties, such as strength aerodynamic shape, or thelike, compared to substrate 12 prior to receiving deposit 14. In someexamples, deposit 14 and substrate 12 include the same composition, suchthat article 10A may have a substantially homogeneous composition afterrepair of substrate 12. In some examples, deposit 14 and substrate 12may include different compositions. For example, a particularcomposition of deposit 14 may be better suited (e.g., more easily bondwith substrate 12 using cold spraying, etc.) as a filler for cracks thana composition of substrate 12.

In some examples, deposit 14 may be configured to protect substrate 12from physical impact or chemical reactants. For example, substrate 12may be a high temperature component, such that portions of substrate 12near surface 16 may face a high temperature environment with reducingagents, such as calcia-magnesia-alumina-sulfur (CMAS), that may damagesubstrate 12. To protect substrate 12 from these agents, deposit 14 mayextend continuously across surface 16 to provide a dense, high strengthbarrier for substrate 12.

In some examples, deposit 14 may be configured to complement substrate12 as a separate structure that provides additional functionality tosubstrate 12. For example, deposit 14 may include a mechanicalcomponent, such as a flange, that is mechanically coupled to substrate12 and configured to perform a different function than substrate 12.

Deposit 14 includes a metal alloy. Metal alloys may have constituentelements that, when subjected to various heat treatments, undergo phasetransformations or migrate from solution to change a microstructure ofdeposit 14. The metal alloy of deposit 14 may include any metal alloywhose properties may change, such as through changes in microstructureor homogeneity of the metal alloy, in response to heat treatmentprocesses. Metal alloys that may be used include, but are not limitedto, Mg-based alloys, Ni-based alloys, Ti-based alloys, Fe-based alloys,Al-based alloys, Co-based alloys, Ta-based alloys, Nb-based alloys,Zn-based alloys, Cr-based alloys, and Cu-based alloys.

Deposit 14 is deposited on surface 16 using cold spraying techniques. Aswill be explained further in FIG. 2 below, cold spraying involvesaccelerating first particles (e.g., heat-treated particles) and secondparticles (e.g., differently-heat-treated or non-heat-treated particles)of the metal alloy constituting at least a portion of deposit 14 towardsurface 16 of substrate 12. Upon impacting surface 16 or a workingsurface of deposit 14, the first and second particles undergodeformation and bond to substrate 12 and/or previously depositedparticles without melting. As a result of cold spray deposition of thefirst and second particles, deposit 14 may have a very densemicrostructure and an interface with substrate 12 that is substantiallyfree of voids, and may be characterized by grain boundaries anddislocation networks formed at interfaces of localized depositscorresponding to deposited first and second particles. Deposit 14 formedfrom the first and second particles may have the same or nearly the samemicrostructure as the first and second particles before spraying, i.e.,there is no thermally induced microstructure change to the particlesthemselves. This may allow better control of the properties of theparticles/domains/regions in the deposit compared to cases where meltingoccurs during spraying.

Deposit 14 includes a first component 18 (e.g., a heat-treatedcomponent) and a second component 20 (e.g., a differently-heat-treatedor non-heat-treated component). While shown as visually differentiatedelements (e.g., interfaces between deposits) in FIG. 1A to emphasize arelationship of first component 18 and second component 20 to firstparticles and second particles, respectively, it will be understood thatdeposits of heat-treated metal alloys corresponding to first component18 and non-heat-treated or differently-heat-treated metal alloyscorresponding to second component 20 may not be differentiated by clearphysical boundaries due to bonding of the metal alloy deposits from theparticles, and that portions of deposit 14 corresponding to firstcomponent 18 and second component 20 may be differentiated by anydifferences in properties derived from heat treatment processes of themetal alloy, as will be described further below.

First component 18 may include any portion of deposit 14 that includes ametal alloy that has undergone heat treatment prior to deposition onsurface 16. Heat treatment may include any process that involvesapplication of heat or cold to a bulk material to change properties ofthe bulk material. First component 18 may include a heat-treated metalalloy formed from a variety of heat treatments including, but notlimited to, annealing, hardening (e.g., aging), surface hardening, andthe like. Mechanical properties of first component 18 may depend on acomposition of first component 18, a type of heat treatment previouslyapplied to first component 18, and/or various parameters used to coldspray heat-treated particles of the metal alloy on surface 16.

Second component 20 may include any portion of deposit 14 that includesa metal alloy that has been subjected to a different heat treatment thanfirst component 18, such as no heat treatment or another heat treatment.While second component 20 may have a same composition (i.e., samechemistry) as first component 18, second component 20 may haveproperties that are different from, and may be complementary to, firstcomponent 18. In some examples, second component 20 includes a metalalloy that has not undergone or been subjected to heat treatment. Forexample, second component 20 may include a metal alloy that has notundergone an amount (e.g., high enough temperature, long enough periodof time) of bulk heating or cooling sufficient to cause a change inmicrostructure or homogeneity of the metal alloy. In some examples,second component 20 includes a metal alloy that has undergone or beensubjected to a different heat treatment than first component 18. In someexamples, the second component may include a heat-treated compositionhaving a same chemistry and different heat treatment as first component18. For example, second component 20 may include a metal alloy that hasundergone a heat treatment that has caused different changes inmicrostructure or homogeneity of the metal alloy than the heat treatmentof first component 18. Certain heat treatments directed toward creatingmore homogeneous microstructures, such as annealing, may complementheat-treatments directed toward precipitating constituents, such ashardening, such that deposit 14 may have a blend of properties thatresult from more than one heat-treatment. First component 18 may includea heat-treated metal alloy formed from a variety of heat treatmentsincluding, but not limited to, annealing, hardening (e.g., aging),surface hardening, and the like.

First component 18 and/or second component 20 may be selected for avariety of properties including, but not limited to, tensile strength,yield strength, hardness, toughness, percent elongation, percentreduction, Young's modulus, and the like. For example, the compositionof the metal alloy of first component 18 and second component 20 and/orthe heat treatment process corresponding to first component 18 may beselected for any properties of either of the heat-treated metal alloyand/or the non-heat-treated metal alloy. As one example in which deposit14 is a barrier coating, first component 18 may be selected for highhardness. As another example in which deposit 14 is a repair joint,first component 18 may be selected for high ductility/elongation, hightoughness, and/or high tensile strength. Properties of first component18 and second component 20, such as tensile strength, elongation, andyield strength, may be measured using test methods such as, for example,ASTM E8 Standard Test Methods for Tension Testing of Metallic Materials,such as for samples that include first component 18 and/or secondcomponent 20, individually or as a blended cold-spray deposit.

In some examples, first component 18 includes a hardened metal alloyformed from a hardening process. For example, hardening may increasetensile strength and ductility (i.e., elongation) of the metal alloy,such that deposit 14 that includes first component 18 may have a greatertoughness than deposits that do not include a hardened component; reducehardness of the metal alloy; create a more stable metal alloy that mayage less in service; and/or modify surface properties of the firstparticles that form first component 18, which may change behaviors ofthe metal alloy within the bulk of deposit 14. In some examples, firstcomponent 18 includes at least one of a precipitation hardened metalalloy, a quenched hardened metal alloy, or a tempered metal alloy. Insome examples, a tensile strength of first component 18 is at leastabout twice as high as a tensile strength of second component 20, suchas at least about 5 times higher. For example, hardened aluminum mayhave a tensile strength of about 20,000 PSI or higher, whilenon-hardened aluminum may have a tensile strength of about 4000 PSI. Insome examples, a percent elongation of first component 18 is at leastabout 50% higher than a percent elongation of second component 20. Forexample, hardened aluminum may have a percent elongation of about 4-8%,while a non-hardened aluminum may have a percent elongation of about2-4%.

As a result of incorporation of both first component 18 and secondcomponent 20, deposit 14 may have bulk properties derived from firstcomponent 18 and second component 20 that are different from propertiesof first component 18 or second component 20 individually. For example,while first component 18 may have improved properties such as tensilestrength and ductility as compared to second component 20, firstcomponent 18 may have increased brittleness, which may increasesusceptibility to cracking. However, second component 20 may moderatethese properties, such that deposit 14 may have values of bulkproperties that are between the individual properties of either firstcomponent 18 or second component 20. A volume ratio of first component18 and second component 20 may be selected to achieve a particular setof properties derived from a relative volume of first component 18 and avolume of second component 20. In some examples, a volume percentage offirst component 18 in deposit 14 is between about 1% and about 99%, suchas between about 10% and about 90%, or between about 30% and about 70%.

First component 18 and second component 20 may be distributed throughoutdeposit 14 in various concentrations and distributions. For example, dueto incremental deposition of first and second particles during coldspraying, distribution (e.g., parallel or normal to surface 16 ofsubstrate 12) of first component 18 and second component 20 may beadjusted temporally and/or spatially. In some examples, first component18 and second component 20 may be distributed substantially homogenouslythroughout deposit 14, such that deposit 14 may have relatively uniformbulk properties. In some examples, first component 18 and secondcomponent 20 may be non-homogeneously distributed throughout deposit 14,such that deposit 14 may have non-uniform bulk properties. For example,a concentration of first component 18 may be higher in a first portionof deposit 14, such as near surface 16, than a second portion of deposit14 to provide properties that may be more suitable for the correspondingportion.

In some examples, in addition to incorporating the metal alloy of firstcomponent 18 and second component 20, deposit 14 may include othercomponents that provide alternative or additional functionality todeposit 14. For example, deposit 14 may include the metal alloy as afirst composition and may include another composition, such as anothermetal, metal alloy, or ceramic, as a third component. For example, thesecond composition may include various properties that complement firstcomponent 18 and/or second component 20.

In the example of FIG. 1A, regions of deposit 14 corresponding to firstcomponent 18 and second component 20 are illustrated as having a similarsize. For example, a substantially uniform size may correspond to moreuniform grain boundaries. However, in some examples, regions of deposit14 corresponding to first component 18 and second component 20 may havedifferent sizes. FIG. 1B is a conceptual cross-sectional view of anexample article 10B including a deposit that includes a first componentand a second component. As illustrated in FIG. 1B, depositscorresponding to first component 18 and second component 20 may havedifferent sizes. Such different sized deposits of first component 18 andsecond component 20 may result from different sized first and secondparticles. In some instances, different size particles may change abehavior of deposit 14 under load. For example, without being limited toany particular theory, second component 20 may have smaller deposits offirst component 18 at an interface of deposits of second component 20and first component 18 boundary. These different sizes of the depositsmay impact deformation at the boundaries when under load, such that thesmaller deposits may lock the boundary and reduce deformation at theboundary.

Articles described herein may be produced using cold spray depositionsystems. FIG. 2 is a conceptual and schematic block diagram of anexample system 30 for forming deposit 14 using cold spraying. System 30is configured to form deposit 14 on substrate 12 by cold spraying firstparticles and second particles of a metal alloy on at least a portion ofsurface 16 of substrate 12. System 30 may include an enclosure 42, whichencloses a stage 44, a cold spray gun 32, a first material source 34, asecond material source 36, and a gas source 38. System 30 may furtherinclude a computing device 40, which is communicatively connected tostage 44, cold spray gun 32, first material source 34, second materialsource 36, and gas source 38.

Article 10 is positioned within enclosure 42. Enclosure 42 maysubstantially enclose (e.g., enclose or nearly enclose) stage 44, coldspray gun 32, first material feed 34, second material feed 36, gassource 38, and article 10. Enclosure 42 may maintain a desiredatmosphere (e.g., an atmosphere that is substantially inert to thematerials from which deposit 14 is formed) around substrate 12 anddeposit 14 during the cold spray technique. In some examples, stage 44may be configured to selectively position and restrain article 10 inplace relative to stage 44 during formation of deposit 14. In someexamples, stage 44 is movable relative to cold spray gun 32. Forexample, stage 44 may be translatable and/or rotatable along at leastone axis to position article 10 relative to cold spray gun 32.Similarly, in some examples, cold spray gun 32 may be movable relativeto stage 44 to position cold spray gun 32 relative to article 10. Insome examples, system 30 may not include enclosure 42 and stage 44. Forexample, system 30 may include a portable device configured to coldspray the heat-treated and non-heat-treated metal alloy particles insitu, such as during a repair. In such examples, system 30 may includetemporary containment as enclosure 42.

First material source 34 and second material source 36 may each beconfigured to supply first particles and second particles, respectively,to cold spray gun 32. Each material source 34 and 36 may include, forexample, a hopper or other container containing first particles andsecond particles, respectively. In some examples, material sources 34and 36 may each include a pneumatic hopper operatively coupled to gassource 38, such that gas source 38 enables material sources 34 and 36 tofeed the first particles and second particles, respectively, to coldspray gun 32. Computing device 40 may be communicatively coupled tofirst material source 34 and second material source 36 to control a rateof flow of first particles and second particles, respectively, frommaterial sources 34 and 36 to cold spray gun 32 via a material feed. Forexample, computing device 40 may control a valve or a feeder system ofthe material feed. In addition to first material source 34 and secondmaterial source 36, system 30 may include other material sources, suchas for a second composition. While shown as separate equipment, in someexamples, first material source 34 and second material source 36 may bethe same equipment. For example, first particles and second particlesmay be pre-mixed prior to being fed into cold spray gun 32.

The first particles and second particles may have propertiescorresponding to localized properties of first component 18 and secondcomponent 20, respectively, of deposit 14, as described in FIG. 1Aabove. For example, the first particles may be selected to providedeposit 14 with particular properties resulting from a particular heattreatment including, but not limited to, tensile strength, yieldstrength, hardness, toughness, percent elongation, percent reduction,Young's modulus, and the like. In some examples, the first particlesinclude at least one of a precipitation hardened metal alloy, a quenchedhardened metal alloy, or a tempered metal alloy. In some examples, atensile strength of the first particles is at least about 10% greaterthan a tensile strength of the second particles. In some examples, apercent elongation of the first particles is at least about 10% greaterthan a percent elongation of the second particles.

The first particles and second particles may include any suitableparticle size. For example, the size range of the first and secondparticles may be between about 1 micrometer (μm) and about 50 μm, suchas between about 5 μm and about 20 μm. The size range of the first andsecond particles may be selected to achieve a selected impact velocity,e.g., a velocity of the particles when impacting surface 16. In someexamples, an average size of the first particles and the secondparticles may be different.

Gas source 38 may be configured to accelerate the first and secondparticles from first material source 34 and second material source 36,respectively. Gas source 38 may include, for example, a source ofhelium, nitrogen, argon, or other substantially inert gas, which mayfunction as carrier of the particles. Gas source 38 may be fluidicallycoupled to a gas feed, which may control a flow rate and/or pressure ofgas delivered to cold spray gun 32. In some examples, the gas feed mayinclude a heater to heat the gas. The pressure of the gas in gas source38 may be sufficient to achieve supersonic velocities of the gas and/orparticles at the outlet of a nozzle. In some examples, the pressure ofthe gas may be between about 0.1 megapascals (MPa) and about 2 MPa, suchas between about 0.5 MPa and about 1.5 MPa. In some examples, thesupersonic velocities may be between about 500 meters per second (m/s)to about 1000 m/s.

Cold spray gun 32 may be configured to entrain the first particles fromfirst material source 34 and the second particles from second materialsource 36 in the flow of gas from gas source 38 through a nozzle. Thenozzle may accelerate the gas and plurality of particles to highvelocities. The resultant high velocity particle stream 48 may bedirected toward surface 16 of substrate 12. Without limiting thedescription to a specific theory, the high velocity of the plurality ofparticles may be sufficient to cause plastic deformation of theparticles upon impact with surface 16 of substrate 12. This process maybe repeated as particles attach to surface 16 and/or other attachedparticles defining a build surface 46 of deposit 14.

System 30 may be configured to control relative movement of highvelocity particle stream 48 with respect to surface 16 of substrate 12and/or build surface 46. For example, directing high velocity particlestream 48 toward substrate 12 may result in deposition of the pluralityof particles on surface 16 of substrate 12 and/or build surface 46. Asillustrated in FIG. 2, the first particles and the second particles mayaccumulate to form deposit 14. For example, high velocity particlestream 48 may be moved over surface 16 and/or build surface 46 until asufficient amount of the heat-treated metal alloy and thenon-heat-treated metal alloy has accumulated to define, at leastroughly, deposit 14. For example, excess metal alloy may be deposited toform a structure with larger dimensions than a final structure ofdeposit 14, then excess metal alloy may be machined away to definedeposit 14. Although not illustrated in FIG. 2, system 30 may alsoinclude a milling device or machining device configured to removedeposited metal alloy to define a final shape of deposit 14.

Computing device 40 may include, for example, a desktop computer, alaptop computer, a tablet, a workstation, a server, a mainframe, a cloudcomputing system, or the like. Computing device 40 may include or may beone or more processors or processing circuitry, such as one or moredigital signal processors (DSPs), general purpose microprocessors,application specific integrated circuits (ASICs), field programmablelogic arrays (FPGAs), or other equivalent integrated or discrete logiccircuitry. Accordingly, the term “processor,” as used herein may referto any of the foregoing structure or any other structure suitable forimplementation of the techniques described herein. In addition, in someexamples, the functionality of computing device 40 may be providedwithin dedicated hardware and/or software modules.

Computing device 40 is configured to control operation of system 30,including, for example, stage 44, cold spray gun 32, material sources 34and 36, and/or gas source 38. Computing device 40 may be configured tocontrol operation of stage 44 and/or cold spray gun 32 to positionarticle 10 relative to cold spray gun 32. For example, as describedabove, computing device 40 may control stage 44 and/or cold spray gun 32to translate and/or rotate along at least one axis to position article10 relative to cold spray gun 32.

Computing device 40 may control at least one of the feed rate of thefirst particles from first material source 34, second particles fromsecond material source 36, pressure from gas source 38, flow rate of thegas from gas source 38, the movement of high velocity particle stream 48relative to article 10, a distance between cold spray gun 32 and buildsurface 46, the angle of the high velocity particle stream relative tobuild surface 46, and a width of overlap between adjacent passes of thehigh velocity particle stream and the velocity of cold spray gun 32relative to build surface 46. Computing device 40 may control at leastone of these parameters to control an amount of material, such asheat-treated metal alloy and non-heat-treated metal alloy, added toarticle 10 at a given time and location and/or to control metallurgicalproperties of the added material. In some examples, cold spray gun 32may be scanned (e.g., translated) relative to deposit 14, and deposit 14will include a general shape corresponding to the scanned path.

The articles described herein may be formed using any suitabletechnique. FIG. 3 is a flow diagram illustrating an example techniquefor forming deposit 14 on surface 16 of substrate 12 that includes coldspraying first particles and second particles of a metal alloy. Thetechnique of FIG. 3 will be described with concurrent reference toarticle 10 of FIG. 1A and system 30 of FIG. 2. In other examples, othersystems may be used to perform the technique of FIG. 3, the technique ofFIG. 3 may be used to form other composite components, or both.

In some examples, the technique illustrated in FIG. 3 may optionallyinclude preparing substrate 12 (50). Preparing substrate 12 may includeany process or series of processes to prepare surface 16 of substrate 12for deposition of deposit 14. In some examples, preparing substrate 12may include forming substrate 12. For example, forming substrate 12 mayinclude forging, casting, or performing other metallurgy techniques todefine a shape of substrate 12. In some examples, preparing substrate 12may include surface preparation of surface 16, such as, for example,abrading surface 16 and/or coating surface 16 with a coating configuredto improve bonding of deposit 14 or to improve mechanical properties orchemical properties of article 10, such as one or more thermal barriercoatings or environmental barrier coatings. In some examples, preparingsubstrate 12 may include treatment of a crack, chip, discontinuity, orother damaged feature for repair by deposit 14. For example, one or moresurfaces of a crack may be smoothed, roughened, or otherwise treated toimprove deposition or bonding of deposit 14 to the surface of the crack.

In some examples, the technique illustrated in FIG. 3 may optionallyinclude selecting, by system 30, a composition of heat-treated particlesand non-heat-treated particles (52). The composition of first particlesand second particles in high velocity particle stream 48 may include arelative composition (e.g., a ratio) of the first and second particles.In some examples, computing device 40 may hold constant the compositionof the first particles and second particles throughout the cold spraydeposition process, such as for a deposit having substantiallyhomogenous properties, while in other examples, computing device 40 mayvary the composition of the first particles and the second particlesduring the cold spray deposition process, such as for a deposit having aspatially varying composition. For example, computing device 40 mayreceive, such as from a user input, a desired composition of deposit 14.The desired composition may represent a relative composition of firstcomponent 18, second component 20, and/or any other composition inresulting article 10.

The technique illustrated in FIG. 3 includes cold spraying, by system30, heat-treated particles and non-heat-treated particles on to at leasta portion of surface 16 of substrate 12 (54). As discussed above inreference to FIG. 1A, cold spraying involves using cold spray gun 32 andgas source 38 to accelerate first particles from first material source34 and second particles from second material source 36 toward surface 16of substrate 12 without melting the first and second particles. Thefirst and second particles may contact surface 16 at velocitiessufficient to cause plastic deformation of the particles and result inattachment or bonding of the particles to surface 16 and/or otherattached particles defining build surface 46. In some examples, coldspraying includes high pressure cold spraying. For example, gas source38 and material sources 34 and 36 may include pressurization systems topressurize each of gases, first particles, and second particles.

In some examples, the technique illustrated in FIG. 3 may optionallyinclude, after cold spraying the first and second particles to formfirst component 18 and second component 20, machining the depositedfirst component 18 and second component 20 to define deposit 14 (56).For example, forming deposit 14 may include cold spraying excess firstcomponent 18 and second component 20 on to surface 16, then machiningaway the excess first component 18 and second component 20. Machiningaway the excess first component 18 and second component 20 may enablesystem 30 to form deposit 14 including more complex geometries, withincreased precision (e.g., within predetermined tolerances), or bothcompared to a technique without machining.

Various examples have been described. These and other examples arewithin the scope of the following claims.

What is claimed is:
 1. A method comprising: cold spraying firstparticles and second particles of a metal alloy on at least a portion ofa surface of a substrate to form a deposit on the surface of thesubstrate, wherein the first particles form a first component of thedeposit and the second particles form a second component of the deposit,wherein cold spraying comprises accelerating the first particles and thesecond particles toward the surface of the substrate without creatingthermally induced changes to a microstructure of the respective firstand second particles, and wherein the first and second particles havebeen subjected to different heat treatments prior to cold spraying. 2.The method of claim 1, wherein the first particles comprise at least oneof precipitation hardened particles, quenched hardened particles, ortempered particles.
 3. The method of claim 1, wherein a volumepercentage of the first component in the deposit is between about 1% andabout 99%.
 4. The method of claim 1, wherein the metal alloy comprisesat least one of a Mg-based alloy, a Ni-based alloy, a Ti-based alloy, aFe-based alloy, an Al-based alloy, a Co-based alloy, a Ta-based alloy, aNb-based alloy, a Zn-based alloy, a Cr-based alloy, or a Cu-based alloy.5. The method of claim 1, wherein the surface comprises a crackedsurface, and wherein forming the deposit further comprises filling thecracked surface with the deposit.
 6. The method of claim 1, wherein atensile strength of the first particles is at least about twice as highas a tensile strength of the second particles.
 7. The method of claim 1,wherein an elongation of the first particles is at least about 50%greater than an elongation of the second particles.
 8. The method ofclaim 1, wherein the metal alloy comprises a first composition, andwherein the method further comprises forming the substrate from a secondcomposition, different from the first composition.
 9. The method ofclaim 1, wherein the first and second particles and the substrate arenot subject to a heat treatment during the cold spraying that wouldfurther modify thermomechanical properties of the first and secondparticles and the substrate.
 10. The method of claim 1, wherein thesecond composition comprises the metal alloy that has not been subjectedto a heat treatment prior to cold spraying.
 11. An article comprising: asubstrate defining a surface; and a deposit on the surface of thesubstrate, wherein the deposit was formed using cold spraying, whereinthe deposit comprises a first component and a second component, whereincold spraying comprises accelerating first particles and secondparticles of a metal alloy toward the surface of the substrate withoutcreating thermally induced changes to a microstructure of the respectivefirst and second particles, and wherein the first and second particleshave been subjected to different heat treatments prior to cold spraying.12. The article of claim 11, wherein the first particles comprise atleast one of precipitation hardened particles, quenched hardenedparticles, or tempered particles.
 13. The article of claim 11, wherein avolume percentage of the first component in the deposit is between about1% and about 99%.
 14. The article of claim 11, wherein the metal alloycomprises at least one of Mg-based alloys, Ni-based alloys, Ti-basedalloys, Fe-based alloys, Al-based alloys, Co-based alloys, Ta-basedalloys, Nb-based alloys, Zn-based alloys, Cr-based alloys, and Cu-basedalloys.
 15. The article of claim 11, wherein the surface comprises acracked surface, and wherein the deposit fills at least a portion of thecracked surface.
 16. The article of claim 11, wherein a tensile strengthof the first particles is at least about twice as high as a tensilestrength of the second particles.
 17. The article of claim 11, whereinan elongation of the first particles is at least about 50% greater thanan elongation of the second particles.
 18. The article of claim 11,wherein the metal alloy comprises a first composition, and wherein thesubstrate comprises a second composition, different from the firstcomposition.
 19. The article of claim 11, wherein the first and secondparticles and the substrate are not subject to a heat treatment duringthe cold spraying that would further modify thermomechanical propertiesof the first and second particles and the substrate.
 20. The article ofclaim 11, wherein the second particles comprise the metal alloy that hasnot been subjected to a heat treatment prior to cold spraying.